IO流，Properties基本功能和遍历

 import java.util.Enumeration;
 import java.util.Iterator;
 import java.util.Properties;
 import java.util.Set;

 public class PropertiesDemo {
     public static void main(String[] args) {
         Properties properties = new Properties();
         properties.put("zhangsan", "23");
         properties.put("lisi", "25");
         properties.put("wangwu", "21");
         properties.put("zhaoliu", "27");
         Set<String> names = properties.stringPropertyNames();
         //使用高级for遍历
         for(String name : names) {
             String value = properties.getProperty(name);
             System.out.println(name + " = " + value);
         }
         //使用迭代器遍历
         Iterator<String> iterable = names.iterator();
         while(iterable.hasNext()){
             String key = iterable.next();
             String value = properties.getProperty(key);
             System.out.println(key +" = " + value);
         }
         //使用枚举遍历
         Enumeration<String> enumeration = (Enumeration<String>)properties.propertyNames();
         while(enumeration.hasMoreElements()) {
             String key = enumeration.nextElement();
             String value = properties.getProperty(key);
             System.out.println(key + " = " + value);
         }
     }
 }